Prior art container transfer systems heretofore have employed a conveyor equipped with container holding devices for holding containers to the conveyor for conveyance from an input station through one or more processing stations to an output station, a container loading mechanism for automatically transferring containers onto the conveyor, and a container unloading mechanism for automatically transferring containers from the conveyor. The container holding devices for receiving and securely gripping open-ended containers have employed an elongated spindle and a chuck mounted for telescoping movement on the spindle. Various types of chucks have been devised including chucks with jaws arranged around a spindle and engageable by a cam on the spindle which controls radial expansion and contraction of the jaws for internally gripping a container. Other chucks have been devised for externally gripping the neck of a container such as shown in U.S. Pat. Nos. 4,625,854 and 4,640,406.